Modified recycled asphalt mixture based on domestic sludge biochar as well as preparation method and application of modified recycled asphalt mixture

Abstract

The invention provides a modified recycled asphalt mixture based on domestic sludge biochar as well as a preparation method and application of the modified recycled asphalt mixture. The preparation method comprises the following steps: S1, taking new asphalt heated to 150-170 DEG C, domestic sludge biochar heated to 180-200 DEG C, coarse aggregate, fine aggregate and mineral powder, RAP heated to 110-130 DEG C, and a pine tar-based regenerant heated to 50-80 DEG C; s2, mixing RAP and a pine tar-based regenerant at the temperature of 180-200 DEG C to obtain a first mixture; s3, jointly mixing the domestic sludge biochar, new asphalt and the first mixture at the temperature of 180-200 DEG C to obtain a second mixture; and S4, jointly mixing the coarse aggregate, the fine aggregate, the mineral powder and the second mixture at 180-200 DEG C to obtain the modified recycled asphalt mixture. According to the invention, the high-performance modified recycled asphalt mixture can be obtained based on the domestic sludge biochar, the pine tar-based regenerant and the RAP.

Description

Technical Field

[0001] The invention relates to a regenerated asphalt mixture, and in particular to a modified regenerated asphalt mixture based on domestic sludge biochar, a preparation method and an application thereof. Background Art

[0002] As a product of domestic sewage treatment, domestic sludge concentrates 30% to 50% of pollutants in domestic sewage and has the dual attributes of "pollution" and "resource". The safe treatment and disposal of domestic sludge and its resource utilization have always been an international research hotspot in the field of sewage treatment. Domestic sludge carbonization technology is a new domestic sludge treatment technology developed in Japan, Europe and the United States in the 1990s. After 2008, China has also gradually carried out technical research on domestic sludge carbonization. After domestic sludge is carbonized by carbonization technology, a large amount of domestic sludge biochar is produced, which is urgently needed to be utilized as a resource.

[0003] Currently, for the regeneration of modified old asphalt, the regeneration agent cannot repair its broken C=C double bonds. The purpose of its regeneration is to adjust the proportion of the four components of the base asphalt in the modified old asphalt to the standard of new asphalt, which makes the resource application of SBS modified RAP difficult. Factory-mixed hot-recycled asphalt mixture is also mainly used in the middle and lower layers of the pavement, and is rarely used in the upper layer.

[0004] The Chinese invention patent application with publication number CN105017788A discloses a method for modifying asphalt and its mixture using biochar, wherein a biochar modifier is prepared using plant carbon sources, and biochar is added to asphalt and its mixture to prepare biochar-modified asphalt and its mixture. Although it improves the performance of ordinary asphalt and its mixture, it does not obtain a modified recycled asphalt mixture, nor does it explore the regeneration agent of RAP, thus failing to realize the resource utilization of RAP, and the biochar used is not domestic sludge biochar; therefore, it does not obtain a high-performance recycled asphalt mixture based on domestic sludge biochar, regeneration agent and RAP.

[0005] In view of this, it is necessary to provide a modified recycled asphalt mixture based on domestic sludge biochar, a preparation method and an application, so as to solve or at least alleviate the technical problem of how to obtain a high-performance modified recycled asphalt mixture based on domestic sludge biochar, pine tar-based regeneration agent and RAP. Summary of the invention

[0006] The main purpose of the present invention is to provide a modified recycled asphalt mixture based on domestic sludge biochar, a preparation method and an application, aiming to solve the technical problem of how to obtain a high-performance modified recycled asphalt mixture based on domestic sludge biochar, pine tar-based regeneration agent and RAP.

[0007] To achieve the above object, the present invention provides a method for preparing a modified regenerated asphalt mixture based on domestic sludge biochar, comprising the steps of:

[0008] S1, take new asphalt heated to 150-170℃; take domestic sludge biochar, coarse aggregate, fine aggregate, and mineral powder heated to 180-200℃; take RAP heated to 110-130℃; take pine tar-based regeneration agent heated to 50-80℃;

[0009] The mass ratio of the new asphalt, the domestic sludge biochar, the coarse aggregate, the fine aggregate, the mineral powder, the RAP, and the pine tar-based regeneration agent is 3-3.2: 0.7-0.9: 40-41: 18.5-20: 1-1.2: 34-36: 0.09-0.11;

[0010] The pine tar-based regeneration agent comprises, by mass percentage, 60-80% pine tar, 10-15% plasticizer, 2-6% tackifier, 1-5% softener, 2-6% pour point depressant, and 2-6% dispersant;

[0011] S2, mixing the RAP and the pine tar-based regeneration agent at a temperature of 180 to 200° C. to obtain a first mixture;

[0012] S3, mixing the domestic sludge biochar, the new asphalt and the first mixing material at a temperature of 180-200° C. to obtain a second mixing material;

[0013] S4, mixing the coarse aggregate, the fine aggregate, the mineral powder and the second mixing material at a temperature of 180-200° C. to obtain the modified recycled asphalt mixture.

[0014] Furthermore, the new asphalt is SBS modified asphalt, in which the mass proportion of SBS is 3.5-4.5%; the mass proportion of old asphalt in the RAP is 4-5%, and the RAP comes from the upper layer of the road surface.

[0015] Furthermore, the domestic sludge biochar is obtained by carbonizing domestic sludge; the mass proportion of organic matter in the domestic sludge is 40-60%; and the particle size of the domestic sludge biochar is not greater than the aperture corresponding to a 100-mesh sieve.

[0016] Furthermore, the domestic sludge biochar contains carbon, oxygen, silicon, aluminum, iron, potassium, calcium, phosphorus, magnesium, nitrogen, hydrogen, titanium, sodium, sulfur and manganese.

[0017] Furthermore, the plasticizer includes epoxidized soybean oil, the tackifier includes C9 petroleum resin, the softener includes waste plastic oil, the pour point depressant includes polymethacrylate, and the dispersant includes acrylamide.

[0018] Furthermore, the pine tar oil includes pyrolysis oil of pine roots and pine branches at 400-500°C.

[0019] Furthermore, the method for obtaining the pine tar-based regeneration agent includes:

[0020] S21, shearing the pine tar oil, the softener, the pour point depressant, and the dispersant together at a temperature of 60 to 85° C. to obtain a first treated product;

[0021] S22, shearing the first treated material, the plasticizer, and the tackifier together at a temperature of 95 to 120° C. to obtain the pine tar-based regeneration agent.

[0022] Furthermore, the particle size of the coarse aggregate has two levels, the particle size of the coarse aggregate in the first level is 9.5-13.2 mm, the particle size of the coarse aggregate in the second level is 4.75-9.5 mm, and the mass ratio of the coarse aggregate in the first level to the coarse aggregate in the second level is 15-30:20-35; the particle size of the fine aggregate is less than 4.75 mm; the mineral powder includes limestone mineral powder.

[0023] The present invention also provides a modified regenerated asphalt mixture based on domestic sludge biochar, which is prepared by any of the preparation methods for the modified regenerated asphalt mixture described above.

[0024] The present invention also provides a use of any of the above-mentioned modified regenerated asphalt mixtures based on domestic sludge biochar in roads.

[0025] Compared with the prior art, the present invention has at least the following advantages:

[0026] The present invention obtains a high-performance modified regenerated asphalt mixture based on domestic sludge biochar, pine tar-based regeneration agent and RAP; the present invention can consume domestic sludge biochar and RAP on a large scale, save non-renewable resources, reduce the cost of asphalt pavement construction, realize its high-value and efficient resource application, and reduce its impact on the environment. The present invention adopts pine tar to replace extracted oil, and combines epoxidized soybean oil, C9 petroleum resin, waste plastic oil, polymethacrylate and acrylamide to prepare an environmentally friendly regeneration agent with excellent performance - pine tar-based regeneration agent, which can fully regenerate heavy traffic asphalt in SBS modified old asphalt; the present invention also adopts domestic sludge biochar modifier to modify SBS modified regenerated asphalt, improves the performance of SBS modified regenerated asphalt mixture, so that it can be better applied to the road surface layer; at the same time, the present invention also optimizes the mixing process, domestic sludge biochar and SBS modified asphalt are added to the mixing pot before the mineral material, so that the pine tar-based regeneration agent, old asphalt and SBS modified asphalt can be fully fused and regenerated, and the domestic sludge biochar can be fully mixed and modified with the SBS modified regenerated asphalt.

[0027] In the present invention, the domestic sludge biochar is different from the conventional biochar, mainly because the domestic sludge biochar contains not only a large proportion of C, but also nutrients such as P, N, K, Ca, and has the characteristics of being porous and adsorbent, and can modify the regenerated asphalt in a targeted manner. The domestic sludge biochar acts on the RAP mixed with the pine tar-based regeneration agent, which can well adsorb the regenerated asphalt and improve the performance of the regenerated asphalt.

[0028] The present invention tests relevant indicators of domestic sludge biochar and SBS modified recycled asphalt mixture. Compared with the same type of SBS modified recycled asphalt mixture and brand-new modified asphalt mixture, the residual stability, freeze-thaw splitting strength ratio and dynamic stability of the modified recycled asphalt mixture based on domestic sludge biochar are better than those of the SBS modified recycled asphalt mixture, and are basically close to those of the brand-new modified asphalt mixture, indicating that domestic sludge biochar can effectively improve the water stability and rutting resistance of asphalt mixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0030] Figure 1 This is the grading diagram of AC-13 asphalt mixture.

[0031] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any methods, equipment and materials of the prior art similar or equivalent to the methods, equipment and materials described in the embodiments of the present invention can also be used to implement the present invention.

[0035] The present invention provides a method for preparing a modified regenerated asphalt mixture based on domestic sludge biochar, comprising the steps of:

[0036] S1, take new asphalt heated to 150-170℃; take domestic sludge biochar, coarse aggregate, fine aggregate, and mineral powder heated to 180-200℃; take RAP heated to 110-130℃; take pine tar-based regeneration agent heated to 50-80℃.

[0037] The mass ratio of the new asphalt, the domestic sludge biochar, the coarse aggregate, the fine aggregate, the mineral powder, the RAP, and the pine tar-based regeneration agent is 3-3.2: 0.7-0.9: 40-41: 18.5-20: 1-1.2: 34-36: 0.09-0.11.

[0038] The new asphalt is SBS modified asphalt, and the mass proportion of SBS in the SBS modified asphalt is 3.5-4.5%; the RAP comes from the upper layer of the road surface; the RAP is SBS modified RAP; the RAP can be specifically understood as: SBS modified asphalt mixture recycled from the old road surface; in the RAP, the proportion of aged asphalt (old asphalt) is 4-5%. In the present invention, the RAP has two grades, the particle size of the first grade RAP is 0-8mm (less than 8mm), and the particle size of the second grade RAP is 8-16mm. The mass ratio of the first grade RAP to the second grade RAP can be 14-16:19-21.

[0039] The domestic sludge biochar is obtained by carbonizing domestic sludge; the present invention uses domestic sludge as a carbon source and adopts a pyrolysis method to prepare the domestic sludge biochar modifier, and specifically adopts an integrated sludge continuous carbonization technology to prepare the domestic sludge biochar modifier; in the present invention, there is no oxygen involved in the entire carbonization process, which is an anaerobic carbonization, and there are no oxides in the product. The process of carbonizing the domestic sludge biochar includes three parts: a pre-drying section, a drying section, and a carbonization section. In the pre-drying section, the domestic sludge with a higher water content is directly contacted with a relatively low temperature hot air for preliminary drying; in the drying section, the domestic sludge with a lower water content is indirectly heated by the high temperature gas through the machine wall, and is continuously evaporated and dried; in the carbonization section, the domestic sludge is indirectly heated to 500-600°C by the high temperature gas through the machine wall, and the domestic sludge is pyrolyzed into biochar.

[0040] The domestic sludge is derived from a domestic sewage treatment plant, and the mass proportion of organic matter in the domestic sludge is 40-60%. The particle size of the domestic sludge biochar is no greater than the aperture corresponding to the 100-mesh sieve; in the present invention, the domestic sludge biochar is ground into powder by a vertical planetary ball mill, and sieved with a 100-mesh sieve, and the sieve is taken to obtain a domestic sludge biochar modifier of the corresponding particle size. In the present invention, the amount of the domestic sludge biochar added is 10-20% of the mass of the fused asphalt (new asphalt + recycled asphalt), and the domestic sludge biochar can be used as a filler in the mixture to replace part of the mineral material.

[0041] In the present invention, the main component of the domestic sludge biochar is C element, and it also contains a small amount of P, N, K, Ca and other elements, all of which have the characteristics of being porous and adsorbent, and can well adsorb asphalt and improve asphalt performance. Specifically, the domestic sludge biochar contains carbon element, oxygen element, silicon element, aluminum element, iron element, potassium element, calcium element, phosphorus element, magnesium element, nitrogen element, hydrogen element, titanium element, sodium element, sulfur element, and manganese element.

[0042] The domestic sludge biochar contains, by mass fraction, 23-25% carbon, 22-25% oxygen, 17-20% silicon, 8-11% aluminum, 4-5% iron, 2.5-3.5% potassium, 1-2% calcium, 1-2% phosphorus, 0.5-1% magnesium, 0.5-1% nitrogen, 0.3-0.8% hydrogen, 0.2-0.6% titanium, 0.2-0.35% sodium, 0.2-0.35% sulfur and 0.1-0.25% manganese.

[0043] In the present invention, the pine tar-based regeneration agent includes or is, by mass fraction: 60-80% pine tar, 10-15% plasticizer, 2-6% tackifier, 1-5% softener, 2-6% pour point depressant, and 2-6% dispersant; the total mass of each component accounts for 100%.

[0044] The pine tar oil is the cracked oil of pine roots and pine branches at 400-500°C; the plasticizer includes epoxidized soybean oil, the tackifier includes C9 petroleum resin, the softener includes waste plastic oil, the pour point depressant includes polymethacrylate, and the dispersant includes acrylamide. In the present invention, the amount of the pine tar-based regeneration agent is 6-10% of the mass of the aged asphalt (old asphalt) in the RAP.

[0045] The method for obtaining the pine tar oil-based regeneration agent includes:

[0046] S21, shearing the pine tar oil, the softener, the pour point depressant, and the dispersant together at a temperature of 60 to 85° C. or 60 to 80° C. for 5 to 15 minutes to obtain a first treated product.

[0047] S22, shearing the first treated material, the plasticizer, and the tackifier together at a temperature of 95 to 120° C. or 100 to 120° C. for 15 to 25 minutes, and cooling to obtain the pine tar-based regeneration agent.

[0048] At present, the main component of most asphalt regeneration agents is extracted oil, which accounts for more than 80% by weight. However, extracted oil is a petroleum-based product and a non-renewable resource. Pine tar oil has the characteristics of wide sources, waste utilization, environmental protection and renewable. It is a renewable resource and can well supplement the missing light components in aged asphalt, disperse the condensed asphaltene in aged asphalt, and reduce the viscosity of aged asphalt, and then use it to replace extracted oil to prepare asphalt regeneration agent.

[0049] In the present invention, the particle size of the coarse aggregate has two grades, the particle size of the coarse aggregate in the first grade is 9.5-13.2 mm, and the particle size of the coarse aggregate in the second grade is 4.75-9.5 mm, and the mass ratio of the coarse aggregate in the first grade to the coarse aggregate in the second grade is 15-30:20-35 or 17.7-19.7:20.9-22.9; the particle size of the fine aggregate is less than 4.75 mm, that is, the fine aggregate is one grade, and the specification is 0-4.75 mm; the mineral powder includes limestone mineral powder, and the particle size of the mineral powder is greater than 75% below the 0.075 mm sieve (that is, the particles not greater than 0.075 mm account for more than 75% of the mineral powder).

[0050] In the research process of the present invention, the RAP extraction and screening are mainly used to determine the screening result and the oilstone ratio; then the coarse aggregate, the fine aggregate, the mineral powder screening results and the RAP extraction and screening results are graded and combined to determine the proportion of each grade of aggregate.

[0051] S2, mixing the RAP and the pine tar-based regeneration agent at a mixing pot temperature of 180 to 200° C. for 50 to 70 seconds to obtain a first mixture.

[0052] S3, mixing the domestic sludge biochar, the new asphalt and the first mixing material together at a mixing pot temperature of 180 to 200° C. for 50 to 70 seconds to obtain a second mixing material.

[0053] S4, mixing the coarse aggregate, the fine aggregate, the mineral powder and the second mixing material together in a mixing pot at 180-200° C. for 100-140 seconds to obtain the modified recycled asphalt mixture.

[0054] In the present invention, the domestic sewage sludge biochar and the new asphalt are mixed before the mineral material, with the purpose of fully blending and regenerating the pine tar-based regeneration agent, the old asphalt in the RAP and the new asphalt, and fully mixing and modifying the SBS modified regenerated asphalt with the domestic sewage sludge biochar.

[0055] In the present invention, the pine tar-based regeneration agent can fully regenerate the heavy traffic asphalt in the SBS-modified old asphalt, and the domestic sewage sludge biochar can improve the performance of the SBS-modified regenerated asphalt mixture, so that it can be better applied to the road surface layer, and the domestic sewage sludge biochar and SBS-modified RAP can be consumed on a large scale, saving non-renewable resources, reducing the cost of asphalt pavement construction, realizing its high-value and efficient resource application, and reducing its impact on the environment.

[0056] The present invention also provides a regenerated asphalt mixture based on domestic sludge biochar, which is prepared by any of the preparation methods for the regenerated asphalt mixture described above.

[0057] The present invention also provides a use of any of the above-mentioned regenerated asphalt mixtures based on domestic sludge biochar in roads, especially in the surface layer of roads.

[0058] The following are specific examples of the present invention:

[0059] In the following cases, the standards for each raw material are as follows:

[0060] 1. The mass proportion of SBS in the new asphalt (SBS modified asphalt) is 4%; the particle size of the coarse aggregate is divided into two grades, the particle size of the first grade coarse aggregate is 9.5-13.2mm, and the particle size of the second grade coarse aggregate is 4.75-9.5mm; the particle size of the fine aggregate is less than 4.75mm; the mineral powder is limestone mineral powder, and the particle size of the mineral powder is greater than 75% below the 0.075mm sieve.

[0061] 2. RAP (modified RAP) is a SBS modified asphalt mixture recycled from old pavement, which comes from the upper layer of the pavement. The mass proportion of aged asphalt (old asphalt) in RAP is 4.5%; the particle size of RAP is divided into two grades, the particle size of the first grade RAP is 0-8mm, and the particle size of the second grade RAP is 8-16mm.

[0062] 3. The domestic sludge biochar comes from domestic sludge, in which organic matter accounts for 52% by mass. The domestic sludge biochar in the present invention is sampled from a domestic sludge carbonization plant.

[0063] After obtaining the domestic sludge biochar, it was ground into powder using a vertical planetary ball mill and sieved with a 100-mesh sieve. The sieved material was taken as the domestic sludge biochar to be used as a modifier; the domestic sludge biochar has a porous structure, and the elemental analysis results of the domestic sludge biochar are shown in Table 1.

[0064] Table 1 Elemental composition of sludge-based biochar

[0065]

[0066] 4. The method of obtaining pine tar-based regeneration agent is:

[0067] Pine tar is heated to 80°C, and waste plastic oil, polymethacrylate and acrylamide are added and sheared together at 80°C for 10 minutes; then, the temperature of the sheared semi-finished product is increased to 100°C, and epoxy soybean oil and C9 petroleum resin are added and sheared together at 100°C for 20 minutes; after cooling, a pine tar-based regeneration agent is obtained; wherein, pine tar is: cracked oil of pine roots and pine branches at about 450°C.

[0068] Among them, by mass fraction, in the pine tar-based regeneration agent, pine tar accounts for 75.0%, epoxidized soybean oil accounts for 11.3%, C9 petroleum resin accounts for 3.8%, waste plastic oil accounts for 2.3%, polymethacrylate accounts for 3.8%, and acrylamide accounts for 3.8%.

[0069] Analysis example 1

[0070] 1. In this analysis example, the performance test of the mixture of domestic sludge biochar and AC-13 modified recycled asphalt was carried out; the mass proportion of asphalt in the mixture was 4.8%.

[0071] 2. In this analysis example, the mass proportion of RAP (SBS modified RAP) in the mixture is 35%; since the mass proportion of old asphalt in RAP is 4.5%, the old asphalt accounts for 1.6% of the asphalt usage in the mixture; the indicators of the old asphalt and the new SBS modified asphalt are shown in Table 2.

[0072] 3. In this analysis example, the dosage of the regeneration agent (pine tar-based regeneration agent) is determined by the penetration index of the regenerated asphalt reaching the requirements of the new asphalt. As shown in Table 2, the dosage of the regeneration agent is determined to be 8%; among which, the dosage of the regeneration agent is: the mass ratio of the regeneration agent and the old asphalt.

[0073] Table 2 Asphalt test results

[0074]

[0075] 4. In this analysis example, the regeneration agent + old asphalt in the mixture is 1.7% (recycled asphalt), so the new asphalt required is 3.1%.

[0076] According to the mass percentage, 10%, 13%, 16%, 19% and 22% of domestic sludge biochar were added to the fused recycled asphalt (calculated as recycled asphalt + new asphalt), respectively, and sheared for 20 minutes using a high-speed shearing machine. The indicators are shown in Table 3. The optimal dosage of domestic sludge biochar at this RAP dosage is 16% of the mass of the fused recycled asphalt, accounting for 0.8% of the mass of the mixture.

[0077] Table 3 Asphalt test results

[0078]

[0079] Example 1

[0080] In this embodiment, the preparation method of the modified recycled asphalt mixture is:

[0081] 1. Combined with the analysis of Example 1, the coarse aggregate in the mixture of domestic sludge biochar and AC-13 modified recycled asphalt ( 9.5~13.2mm ) , coarse aggregate( 4.75~9.5mm ) The mass ratio of fine aggregate, RAP, mineral powder, domestic sludge biochar, new asphalt and regeneration agent is 18.7:21.9:19.3:35:1.1:0.8:3.1:0.1; RAP has two gears, the particle size of the first gear RAP is 0-8mm, and the particle size of the second gear RAP is 8-16mm. The mass ratio of the first gear RAP and the second gear RAP is 15:20.

[0082] Based on this, the recycled asphalt mixture in this embodiment is prepared according to the mass ratio of new asphalt, domestic sludge biochar, coarse aggregate, fine aggregate, mineral powder, RAP, and pine tar-based regeneration agent of 3.1:0.8:40.6:19.3:1.1:35:0.1; among them, the mass ratio of the first-grade coarse aggregate and the second-grade coarse aggregate is 18.7:21.9, and the mass ratio of the first-grade RAP and the second-grade RAP is 15:20.

[0083] 2. Heat the new asphalt to 160°C, heat the domestic sludge biochar, coarse aggregate, fine aggregate and mineral powder to 190°C, heat the RAP to 120°C, and heat the pine tar-based regeneration agent to 60°C.

[0084] 3. Add RAP and pine tar-based regeneration agent to a mixing pot at 180°C and mix for 60 seconds (the mixing temperature is set to 180°C), then add domestic sludge biochar and new asphalt to the mixing pot and mix for 60 seconds (the mixing temperature is set to 180°C), and finally add coarse aggregate, fine aggregate and mineral powder to the mixing pot and mix for 120 seconds (the mixing temperature is set to 180°C) to obtain a recycled asphalt mixture.

[0085] 4. The grading curve of this embodiment is shown in Figure 1 As shown; the testing indicators of recycled asphalt mixture are Marshall stability, residual stability, freeze-thaw splitting strength ratio, and dynamic stability. Please refer to Analysis Example 2 for details.

[0086] Comparative Example 1

[0087] 1. Use SBS modified asphalt to conduct performance test of AC-13 modified asphalt mixture.

[0088] 2. In AC-13 asphalt mixture, coarse aggregate ( 9.5~13.2mm ) , coarse aggregate ( 4.75~9.5mm ) , fine aggregate, mineral powder, new asphalt is 26.7:30.5:34.2:3.8:4.8; the gradation curve of this comparative example is shown in Figure 1 As shown, the synthetic gradation is basically close to that in Example 1.

[0089] 3. Heat the new asphalt to 160°C; heat the coarse aggregate, fine aggregate and mineral powder to 190°C.

[0090] 4. Add coarse aggregate, fine aggregate and new asphalt into a mixing pot at 180°C and mix together for 60 seconds (the mixing temperature is set to 180°C), then add mineral powder into the mixing pot and mix together for 120 seconds (the mixing temperature is set to 180°C) to obtain asphalt mixture.

[0091] In this comparative example, the testing indicators of the asphalt mixture are Marshall stability, residual stability, freeze-thaw splitting strength ratio, and dynamic stability. Please refer to Analysis Example 2 for details.

[0092] Comparative Example 2

[0093] Compared with Example 1, this comparative example omits the pine tar-based regeneration agent (adaptively adjusting the ratio of each component), and other conditions remain unchanged; specifically, as follows:

[0094] 1. In this comparative example, the recycled asphalt mixture is prepared according to the mass ratio of new asphalt, domestic sludge biochar, coarse aggregate, fine aggregate, mineral powder and RAP of 3.2:0.8:40.6:19.3:1.1:35; among them, the mass ratio of the first-grade coarse aggregate and the second-grade coarse aggregate is 18.7:21.9, and the mass ratio of the first-grade RAP and the second-grade RAP is 15:20.

[0095] 2. Heat the new asphalt to 160°C, heat the domestic sludge biochar, coarse aggregate, fine aggregate and mineral powder to 190°C, and heat the RAP to 120°C.

[0096] 3. Add RAP to a mixing pot at 180°C and mix for 60 seconds (the mixing temperature is set to 180°C), then add domestic sludge biochar and new asphalt to the mixing pot and mix for 60 seconds (the mixing temperature is set to 180°C), and finally add coarse aggregate, fine aggregate and mineral powder to the mixing pot and mix for 120 seconds (the mixing temperature is set to 180°C) to obtain a recycled asphalt mixture.

[0097] 4. The testing indicators of recycled asphalt mixture are Marshall stability, residual stability, freeze-thaw splitting strength ratio, and dynamic stability. Please refer to Analysis Example 2 for details.

[0098] Comparative Example 3

[0099] Compared with Example 1, this comparative example omits the domestic sludge biochar (adaptively adjusts the ratio of each component), and other conditions remain unchanged; specifically, as follows:

[0100] 1. In this comparative example, the recycled asphalt mixture is prepared according to the mass ratio of new asphalt, coarse aggregate, fine aggregate, mineral powder, RAP, and pine tar-based regeneration agent of 3.1:40.6:19.3:1.9:35:0.1; among which, the mass ratio of the first-grade coarse aggregate to the second-grade coarse aggregate is 18.7:21.9, and the mass ratio of the first-grade RAP to the second-grade RAP is 15:20. 。

[0101] 2. Heat the new asphalt to 160°C, heat the coarse aggregate, fine aggregate and mineral powder to 190°C, heat the RAP to 120°C, and heat the pine tar-based regeneration agent to 60°C.

[0102] 3. First add RAP and pine tar-based regeneration agent into a mixing pot at 180°C and mix for 60 seconds (mixing temperature is set to 180°C), then add new asphalt into the mixing pot and mix for 60 seconds (mixing temperature is set to 180°C), and finally add coarse aggregate, fine aggregate and mineral powder into the mixing pot and mix for 120 seconds (mixing temperature is set to 180°C) to obtain recycled asphalt mixture.

[0103] 4. The testing indicators of recycled asphalt mixture are Marshall stability, residual stability, freeze-thaw splitting strength ratio, and dynamic stability. Please refer to Analysis Example 2 for details.

[0104] Comparative Example 4

[0105] Compared with Example 1, this comparative example omitted the pine tar-based regeneration agent and the domestic sludge biochar, and other conditions remained unchanged; the details are as follows:

[0106] 1. In this comparative example, the recycled asphalt mixture is prepared according to the mass ratio of new asphalt, coarse aggregate, fine aggregate, mineral powder and RAP of 3.2:40.6:19.3:1.9:35; among which, the mass ratio of the first-grade coarse aggregate to the second-grade coarse aggregate is 18.7:21.9, and the mass ratio of the first-grade RAP to the second-grade RAP is 15:20. 。

[0107] 2. Heat the new asphalt to 160℃, heat the coarse aggregate, fine aggregate and mineral powder to 190℃, and heat the RAP to 120℃.

[0108] 3. Add RAP to a mixing pot at 180°C and mix for 60 seconds (the mixing temperature is set to 180°C), then add new asphalt to the mixing pot and mix for 60 seconds (the mixing temperature is set to 180°C), and finally add coarse aggregate, fine aggregate and mineral powder to the mixing pot and mix for 120 seconds (the mixing temperature is set to 180°C) to obtain a recycled asphalt mixture.

[0109] 4. The testing indicators of recycled asphalt mixture are Marshall stability, residual stability, freeze-thaw splitting strength ratio, and dynamic stability. Please refer to Analysis Example 2 for details.

[0110] Comparative Example 5

[0111] Compared with Example 1, this comparative example changes the preparation method of the recycled asphalt mixture, and other conditions remain unchanged; the details are as follows:

[0112] RAP and pine tar-based regeneration agent are first added to a mixing pot at 180°C and mixed for 60 seconds (the mixing temperature is set to 180°C), then the coarse aggregate and fine aggregate are added to the mixing pot and mixed for 60 seconds (the mixing temperature is set to 180°C), and then the new asphalt is added to the mixing pot and mixed for 60 seconds (the mixing temperature is set to 180°C), and finally the domestic sludge biochar and mineral powder are added to the mixing pot and mixed for 60 seconds (the mixing temperature is set to 180°C) to obtain a modified recycled asphalt mixture.

[0113] In this comparative example, the testing indicators of the recycled asphalt mixture are Marshall stability, residual stability, freeze-thaw splitting strength ratio, and dynamic stability. Please refer to Analysis Example 2 for details.

[0114] Analysis example 2

[0115] The asphalt mixtures in Example 1 and Comparative Examples 1-5 were tested using the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011); as shown in Table 4, by comparing Example 1 with Comparative Example 1, it can be seen that the performance of the modified recycled asphalt mixture based on domestic sludge biochar is basically close to that of the new AC-13 modified asphalt mixture.

[0116] Compared with Comparative Example 2, Comparative Example 3 and Comparative Example 4, it was found that pine tar-based regeneration agent and domestic sludge biochar both play an important role in improving the performance of AC-13 modified recycled asphalt mixture. If one of them is missing, the performance of the mixture will be significantly reduced.

[0117] Compared with Comparative Example 5, it was found that the improved mixing process, i.e., adding the domestic sludge biochar and SBS modified asphalt (new asphalt) into the mixing pot before the mineral material, enabled the AC-13 modified recycled asphalt mixture to obtain better performance, indicating that the pine tar-based regeneration agent, old asphalt and SBS modified asphalt can be more fully integrated and regenerated during the mixing process, and that the domestic sludge biochar can be fully mixed and modified with the SBS modified recycled asphalt.

[0118] Table 4 Asphalt mixture test results

[0119]

[0120]

[0121] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a modified regenerated asphalt mixture based on domestic sludge biochar, characterized in that: Includes steps: S1, take new asphalt heated to 150-170℃; take domestic sludge biochar, coarse aggregate, fine aggregate, and mineral powder heated to 180-200℃; take RAP heated to 110-130℃; take pine tar-based regeneration agent heated to 50-80℃; The mass ratio of the new asphalt, the domestic sludge biochar, the coarse aggregate, the fine aggregate, the mineral powder, the RAP, and the pine tar-based regeneration agent is 3-3.2: 0.7-0.9: 40-41: 18.5-20: 1-1.2: 34-36: 0.09-0.11; The pine tar-based regeneration agent comprises, by mass percentage, 60-80% pine tar, 10-15% plasticizer, 2-6% tackifier, 1-5% softener, 2-6% pour point depressant, and 2-6% dispersant; S2, mixing the RAP and the pine tar-based regeneration agent at a temperature of 180 to 200° C. to obtain a first mixture; S3, mixing the domestic sludge biochar, the new asphalt and the first mixing material at a temperature of 180-200° C. to obtain a second mixing material; S4, mixing the coarse aggregate, the fine aggregate, the mineral powder and the second mixing material at a temperature of 180-200° C. to obtain the modified recycled asphalt mixture.

2. The method for preparing the modified recycled asphalt mixture according to claim 1, characterized in that: The new asphalt is SBS modified asphalt, in which the mass proportion of SBS is 3.5-4.5%; the mass proportion of old asphalt in the RAP is 4-5%, and the RAP comes from the upper layer of the road surface.

3. The method for preparing the modified regenerated asphalt mixture according to claim 1, characterized in that: The domestic sludge biochar is obtained by carbonizing domestic sludge; the mass proportion of organic matter in the domestic sludge is 40-60%; and the particle size of the domestic sludge biochar is not greater than the aperture corresponding to a 100-mesh sieve.

4. The method for preparing the modified regenerated asphalt mixture according to claim 1, characterized in that: The domestic sludge biochar contains carbon, oxygen, silicon, aluminum, iron, potassium, calcium, phosphorus, magnesium, nitrogen, hydrogen, titanium, sodium, sulfur and manganese.

5. The method for preparing the modified regenerated asphalt mixture according to claim 1, characterized in that: The plasticizer includes epoxidized soybean oil, the tackifier includes C9 petroleum resin, the softener includes waste plastic oil, the pour point depressant includes polymethacrylate, and the dispersant includes acrylamide.

6. The method for preparing the modified regenerated asphalt mixture according to claim 1, characterized in that: The pine tar oil comprises pyrolysis oil of pine roots and pine branches at 400-500°C.

7. The method for preparing the modified regenerated asphalt mixture according to claim 1, characterized in that: The method for obtaining the pine tar-based regeneration agent includes: S21, shearing the pine tar oil, the softener, the pour point depressant, and the dispersant together at a temperature of 60 to 85° C. to obtain a first treated product; S22, shearing the first treated material, the plasticizer, and the tackifier together at a temperature of 95 to 120° C. to obtain the pine tar-based regeneration agent.

8. The method for preparing the modified regenerated asphalt mixture according to claim 1, characterized in that: The particle size of the coarse aggregate has two levels, the particle size of the first level is 9.5-13.2 mm, the particle size of the second level is 4.75-9.5 mm, and the mass ratio of the first level to the second level is 15-30:20-35; the particle size of the fine aggregate is less than 4.75 mm; the mineral powder includes limestone mineral powder.

9. A modified recycled asphalt mixture based on domestic sludge biochar, characterized in that: The modified recycled asphalt mixture is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the modified recycled asphalt mixture based on domestic sludge biochar as claimed in claim 9 in roads.

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